Synchronous dynamic random access memory (SDRAM) is one type of computer-based device memory. While standard forms of DRAM have an asynchronous interface (that is, an interface that reacts immediately to changes in control inputs), SDRAM has a synchronous interface, meaning that it waits for a clock signal before responding to control inputs. SDRAM synchronizes with the computer-based device's system bus and processor.
Current electronic circuit designs are migrating from single data rate (SDR) SDRAM to double data rate (DDR) SDRAM to adjust for changing industry needs. With DDR SDRAM, data is clocked both on the rising edge and on the falling edge of the clock, and effectively doubling the raw bandwidth over SDR SDRAM. Today, multiple instances of DDR SDRAM are widely used in computers, servers, storage, and networking and communication equipment. DDR SDRAM is quickly becoming the standard for high-density, low-cost memory designs.
Dynamic memory devices (such as DDR SDRAM) require a periodic refresh (that is, an electrical charge) to keep memory contents (data) intact. The high levels of instantaneous current required for refreshing multiple high-density DDR SDRAM elements is unsustainable for the typical power sources used in the computer-based devices described above. Overcompensating for these instantaneous current demands with additional electrical energy increases power consumption and results in a less efficient electronic circuit design.